Construction principles

The corbelling construction or "overhanging", when each consecutive layer of stones reaches across the lower layer, is in fact planar and can be seen in the cross section. Theoretically it could serve to form a cylindrical arch, but the first constructions were small and built from a circular ground plan with corbelling used to significantly reinforce the structure. Cross sections point out two layers: the internal construction and outer framework, the latter serving as a counterweight and roofing material. The internal structure can be built only in one way, while possibilities for the external structure are numerous.

Construction of the dry wall begins with the wall, which is at first singular, double, conical or composed. Interestingly the singular wall is exquisitely accurately composed built just as the double wall, even though it is a meter and forty centimetres high. The most practical is the double bonded wall, which includes masonry (construction) of both perimeter walls and in-filling, thus easing building and quickening construction.

Corbelling is in principle a planar construction overhanging in section, done by laying stones on top of each other, with the higher layer overhanging the lower one. The utility of such construction is its' very steep pitch, thus counterweights on the outer side are built to reduce the angle to some 60 degrees (on average).


The wall: construction of the wall consists of longitudinal and cross- layed stones, covered all the vertical joints between them

The ground plan of corbelling is circular: thus we avoid problems with corners or producing planar forces.

All in all the section is triangular and the ground plan circular, with corbelling providing an exceptionally stabile and strong construction, which allows compositions exceeding ten meters in diameter.

In professional building this is the structure of the Atreus treasury, which is even larger, but built systematically, with knowledge and partly carved stone layers (thus presenting a cupola in its interior). The difference between corbelling and cupolas is that in corbelling layers are horizontal, graded, while in cupolas they perpendicularly follow the construction plane.


Corbelling is the principle of stratifying the stones in cross section, in ground plan it is mostly circular

In corbelling only the internal, load bearing construction is uniform, with the external layer serving as a coat, which is individual, different and expresses the builders intuition.

 


Vernacular architecture: corbelling at the bridge is simple, but brilliant construction (Matmata, Tunisia)
version for print